Process for treating hydrocarbon oils



J'une 6, 1933. J. c. BLACK PROCESS FOR TREATING' HYDROCARBON OILS Filed June 15, 1926 Patented June 6, 1933 ff UNITED STATES A PATENT ori-ICE y JOHN C.' BLACK, OF LOS ANGELES, CALIFORNIA, ASSIGTN'OR TO GASOLINE PRODUCTS COMPANY, INC., OF WILMINGTON, DELAWARE, A CORPORATION OF DELAWARE PROGESS FOR '.IFBFSLA'PINGI HIDROCA'BBON OILS Application led .Tune 15,

This process relates to an improvement in the art of cracking hydrocarbons to produce lower boiling point hydrocarbons from those -of higher boiling point. l l l This invention also relates to a process of cracking petroleum oils wher'ein a body of oil is heated to a cracking temperature and main- .tained at an active cracking temperature over a prolonged period of time and introducing l into the body of oil at the termination of its cracking period a cooler stream of 011 to check the cracking reaction of `the main stream of oil and simultaneously increase the heat of the injected oil to -a cracking temperature whereby an increased yield o gasoline is obtained, an increased yield of recycle stock, better operative conditions anddecreased production of carbonaceousmaterial are secured.

In my Patent 1,456,419, there is described a process for the production of lower boiling point hydrocarbons from those of higher boiling point which comprises preheating' the oil in a heating coil to the point of active decomy position. The oil thus heated is then subjected to a further heat treatment where it is maintained at the temperature attained in the 1 preheating coil and the endothermic heat of the cracking reaction supplied. In passing through the second heating or cracking coil the hydrocarbons are subjected to the cracking temperature andv maintained for a Sullicient length of time to obtain the desired cracking eli'ects. In this coil thel endothermic heat of the cracking reaction is supplied.`

The streamof oil is kept under sufficient pressure to prevent substantial vaporization. The hydrocarbons passing from the cracking or reaction coils are thenpassed either to a 40 carbon settling chamber or reaction chamber for further decomposition and carbon deposition. In the present invention the above mentioned principle of operation is employed but I split the advancing stream of oil at a chosen pointv in the series of coilsand conduct one of. the streams `which I denominate the bypass `stream into the lower or final passes of the reaction coil. Thisintroduction of the by-pass stream into the reaction coils is made 192e. 'serial No. 116,217.

possible for the reason that there is a difference `in pressure between the point of the bypass connection and the point of re-entrance into the reaction coils which is represented by vthe (pressure drop due to friction between the tw points. By this procedure several n advantages are to be gained which assist in the operative control of the process and also an increased yield of gasoline or low boiling point hydrocarbons may result as will appear as I describe the process in more detail.

If I operated my process with the by-pass connection closed and passed through the system of coils a given quantity of hydrocarbons, I would obtain a certain percentage of decomposed hydrocarbonsat the temperature employed, and I would find thatl the final passes of the reaction coil would gradually foul with carbon and the apparatus would have to be shut down to be cleaned. I have found that if I by-pass a portion of the stream of hydrocarbons and inject the by-passed portion into the nal passes of the reaction coil that I will obtain a greater yield of decomposed hydrocarbons in that portion of the stream passing through the main reaction coil than if the whole stream passed through. I also have found that the fouling of the tubes is very materially lessened by the injection of the by-pass stream and furthermore, I have found that the hydrocarbons of the by-pass stream arealso partially decomposed by theadmixture with the hotter hydrocarbons of the main stream, and also by the heating effect derived from the furnace while passing through the final passes of the reaction coil.

- The above may be understood by the consideration of the following. While I do not p limit myself to the theory here advanced I believe the same to be a probable explanation 'f of the phenomena observed. It is apparent the oil becomes dirty. The oil stream and the fire are so manipulated as to maintain the temperature of the stream at the chosen cracking temperature. Any transfer of heat 5 that results then goes to carbonize the heavy causes the formation of a large amount ofl gas which builds up a high vapor pressure, which may, if carried to excess, exceed the operating pressure and interferes with the operation of the process.

The introduction of a partially heated uncracked oil into the final passes avoids this difficulty, since the latter oil tends to absorb heat by having its sensible heat raised by the cracked oil entering the final passes, thereby lowering the temperature of the cracked oil. The partially cooled stream then absorbs heat from the combustion gases and the tube wall surface, to have its temperature raised to substantially the desired cracking point, and the uncracked oil further' absorbs heat due to its absorption of heat of reaction. There is therefore a large transfer of heat from the combustion gases to the oil passing through the final passes of the coil in the present invention. The tube is kept from overheating and the excessive surface carbonization, as above described, is prevented.

By the present invention I am enabled to obtain a combinedyield of cracked or decomposed hydrocarbons equal to or better than the yield obtained by a single stream operat1on, and at the same time get better operative conditions as regards fouling and timel on stream. c

Furthermore, by the injection of the bypass stream the carbonaceous material deposited in the reaction coil is of a softer composition and is more readily removed in the blowing) down operation and the heaters can be put ack on stream with less loss of time. I prefer to use multiple connections on the header so that the temperature of by-ass the y-pass stream can be varied by manipu` lation of the valves, whereby the main stream may be tapped at several points in the heating coil as the heating progresses. The temperature and uantity of the by-pass stream should be so c osen that the temperature of the admixed streams may be such that decomposition of the by-passed stream may be partially accomplished and to obtain a temperature of the mixture such that the decomposition is checked or reduced in the main stream of hydrocarbons, and the Acarbon of decomposition is minimized and de osited fromv a cooler liquid suspension. T is, as

.cause or another, is not complete.

ent 1,456,419.

The 'hydrocarbons emerging from the reaction coil may be passed to a carbon depositing chamber or reaction chamber where the carbonaceous material may be deposited, and further decomposition of the hydrocarbons may be effected if the reaction, through one On the other hand, the hydrocarbons may be passed through a heat exchanger wherein the heat is lreduced to a point suitable for subsequent fractionation upon release of pressure and discharge into a suitable fractionating apparatus.

The operation of the heat exchanger may be varied at will by the regulation of the by-passon the incoming raw stock so that the temperature of the hydrocarbons upon release of pressure will permit those fractions to vaporize that ,are desired and the residue to separate out.

In the drawing, I show a single heat exchanger connected to the direct discharge line and also to the carbon precipitating chamber using valves properly located to cut in or out either branch. Although in practice I prefer to use one system or the other whereby the valves may be eliminated. Whether I use the reaction chamber or go direct to the heat exchanger and fractionating apparatus largely depends upon the nature of the hydrocarbons. If I am working with a heavy oil I would prefer to by-pass the reaction chamber or cut it olf entirely whereas with a lighter oil it may be found advantageous to use the reaction chamber if it is found that a better conversion of the hydrocarbons is obtained or if the carbonaceous material is' more eectively handled by its use.

In this process I use such a pressure imposed by mechanical means upon the hydrocarbons during the'decomposit-ion stage of the process as to overcome the vapor pressure of the mixture of hydrocarbons. Thisfpre'ssure will vary with each particular grade of hydrocarbons and to the amount of decomposition to which the hydrocarbons have been subjected. This pressure should be predetermined for each individual stock under treatment for if substantial vaporization is permitted carbonaceous deposits will soon form and curtail the operation of the process.

As an illustration of the process I Amay by-pass twenty percent of the stream through the by-pass connection at a temperature of say 625 F. and combine it in the last pass or passes of'the reaction coil, wherein it meets a volume four times as great at a temperature of say 890"v F., the temperature of the mixture is then 837o F., and in passing through the inal passes of the coil it may attain a temperature of 850 F. The result is this: the main stream (which7 in this case is 80% of the total stream entering thesystem) would attain 80 per cent of the velocity of the total stream in this case, and consequently would remain in its reaction coil up tothe point of injection, 20/80 or 25 lper cent longer time and thereby increase its decomposition above what it would have attained if it had passed through at the rate of the'total stream.l tically into the .reaction coil but upon admixture with the main stream it is instantaneously heated from 625 to 837 which increase in temperature is suilicient to partially decompose it, and it will also be further decomposed in passing through the final passes of the reaction coil where it will 'attain a. temperature of 850 F. or more. The lowering of the temperature of the main stream from 890 to 837 F. will check the decomposition of the main stream with its resultant carbon decomv position and the lower passes of the coil will be materially freed from fouling. The prevention of fouling is also assisted by the fact that the hydrocarbonsv passing through the final passes of the reaction coil can absorb heat from the furnace without being heated above a goodoperative temperature, whereas if the hydrocarbons had/entered the final passes of the reaction coil at 890 F. and passed out at the same temperature, practically no heat would be transferred to the hydrocarbons other than the enclothermic heat of reaction, and as a result the steel of the tubes would become overheated withv a tendency to burn out and carbon would rapidly form on the inside circumference of the tubes and in a short time would cause plug-V ging of the tubes, necessitating shutting down to clean them out.

Instead of lay-passing the reheated oil and introducing the same into t e final passes to meet the advancing stream of cracked hydrocarbons, a cold uncracked oil may be introduced into the final passes of'the cracking coil. By regulating the point of introduction of the oil in the cracking coil so as to increase the length of time and the heating effect which the Vcold oil receives analogous results may be obtained. Inoperatin in this way care must betaken to regulate oth the quantity of oil introduced and the point of introduction.

The invention will be better understood by reference to the .drawing'which shows schematically an embodiment of myinvention.

Referring to the. drawing, 1 represents a heating f urnace and 2 represents the primary heating coil.-v 2 is a crossover between coils 2 and 4; 3is a heating furnace and 4 is the secondary heating coil. 5 represents the final The 20% by-passed stream is pracuncracked at the point of entrancepipe 28 and-connects with economizer coil 6 and 11 is a valve in the cross connection between pipe 28 and the entrance to the series of coils 2 and 4. 12 connects the outlet of the coils 2 and 4 with the reaction cham ber through pipe 13 and valve 13 and pipe 14 and valve 14. In pipe 12 is a valve 12.

Pipe 12 connects with the heat exchanger 15.l

16 is an outlet connection from heat exchanger 15 to the fractionating tower 17 ad 16" is a pressure regulating and discharge valve inkpipe 16. 18 is a connection for conducting the heavy ends and gas oil cut from the fractionating tower 17 to the cooler. 19 is a connection from the cooler to the gas oil tank and 19 is a valve thereon. 20 is a connection to the gas oil tank and connects with pump 21 through pipe 22 and valve 22. 20 also connects with pump 23 through pipe 24 and valve 24. 25 is a connection from pump 23 connecting with a spray connection 26 in the fractionating tower 17. 27 is a connection from pump21 to the gas oil supply tank through connection 41, and 27 is a valve 1n 28 is a discharge connection' from the pump 21 to the heat exchanger 15, and 28 is a valve in pipe 28. 29 is a by-pass connection around the heat exchanger 15 and connects into pipe 28. 29 is avalve in pipe 29; 30 is a pump connected to the heavy oil tank through connection 31 and valveA 31', and to the gas oil tank through connection 32 and valve 32. 33 is a discharge connection from pump 30 connecting with the economizer coil.6 and 33 is a valve in pipe 33.

The numeral 35 designates a vapor pipe connecting the fractionating tower 17 with the condenser 36, which in turn is connected with the light oil tank through connection 37 yand look box 38. 39 is a gas vent connecting with the gas header 40. 41 is a connection between the supply tank and pumps 21 and 30. 41 is a valve in pipe 41 and "42 is a connection from the bottom ofthe fractionating tower 17 connecting with the residue tank, and 42 is a valve in pipe 42. 43,

pipe 27.

' 44, 45, 46, 58 lare pyrometer connections on the various coils, 47 is a blow down connection and 47 is a blow down valve on pipe 47. 48 isa blow down connection from the -reaction chamber and 48 is the blow down valve on pipe 48. 49 and" 50 are pressure gauges on the pumps 21 and 30 respectively. 51 is a terminal pressure gauge to indicate the .pressure at the point of pressure release and discharge. 52 is a connection to the recycle oil tank and 52 is a valve thereon. 53 is a connection from pipe 33 connecting to the final passes of coil 4 and 53 is a valve in pipe 53. 54 is a connection between header 7 and pipe 6, and 54 is a valve in pipe 54. 55 is a valved connection between pipe 6 and the coil 2. 56 is a valve on header 7 between the inlet of coil 6 and pipe 54. 57 is a connection 0 from the water tank to the pump 21 and valve 57 is in pipe 57.

I will now describe the operation of my process. It will be noted that ll can inject various grades of oil into the iinal passes of the secondary heating coil, such as fresh gas oil from the gas oil supply tank, gas oil from the re-run gas oil tankand heavy oil from the heavy oil tank or combination of these various grades of oil, whichever method -is used is optional with the operator and will depend upon the class of hydrocarbons being handled.

Let us assume first that We are handling gas oil in pump 21 and heavy oil in pump 30; pump 21 takes suction on the re-run gas oil tank and discharges it through the heat exchanger 15, if too much cooling effect on the i outgoing oil fromthe heat exchanger is produced by passing all the oil from pump 21 through the heat exchanger, then the valve 29 in by-pass 29 is so regulated that'the proper temperature is obtained in the oil entering the fractionating tower 17, that is by proper regulation of valve 29 l can bypass any quantity of oil l desire around the heat exchanger and thereby regulate the temperature of the outgoing oil, the valve 28 vis also regulated in conjunction with valve 29. The oil now passing through 28 enters the coil 2 in furnace 1 (valve 11 being closed and 11 being open and valve 55 being closed) and is heated to a temperature as determined by pyrometer 43 equal to approximately the temperature chosen for the cracking reaction. (This temperature depends upon the character of the oil-a higher temperature for the light oils and a lower temperature for the heavier oils.) It then passes over to coil 4 through crossover 2 and is supplied with heat from the furnace 3 in suficient quant-ities to approximately maintain its temperature uniform throughout itsA passage through coil 4, that is at the temperature chosen for the reaction and which it attained in coil 2 as stated above. rlhat is, the temperature indicated by pyrometer 44 is equal to approximately that at 43. The

011 now enters the final passes of coil 4 which is shown as a single layer of tubes and marke-d 5 on the drawing. However, the final passes of coil 4 may consist of any number of layers of tubes but for convenience is shown as one layer. Coincident with the gas oil entering the final passes of coil 4 there is introduced into the stream a second supply of oil which has been pumped from the heavy.'i oil tank by pump 30 and discharged through pipe 33 to the economizer coil 6 located in the waste combustion gas spaces of furnaces 1 and 3, valve 33 being open and valve 53 closed and valve 54 and 10 being open.

rlhe temperature of this second supply of oil is maintained at a lower temperature than the gas oil stream and is determined by pyrometer 45. The two commingled streams of oil now pass through the final passes 5 of coil 4 wherein the 'mixture of oils may function, in the above described manner. The mixture of oils now passes out of the heating coils (its temperature being determined by pyrometer 46) into pipe connection 12 which connects lwith the reaction chamber or it may go direct to the heat exchanger 15. lf I elect to pass the oil through the reaction chamber I would close valve 12 and open valves 13 and 14, then pass the oil through the heat exchanger where its temperature is reduced and regulated as eX- plained above. It then discharges through pipe 16 and pressure reducing and discharge valve 16 to the fractionating tower 17 where the various hydrocarbons are separated, such as a residue that may be drawn off thru pipe 42 and valve 42 and run to the tank marked Yxssidue oil. Also a heavy condensate may be separated and drawn off through pipe connection 18 passed through the cooler and through pipe 19 and valve 19 to the re-run gas oil tank to be re-run. There is a by-pass connection 52 and valve 52 to permit of withdrawing a portion of the re-run gas oil into the tank marked Recycle oil7 for subsequent recirculation wherein it is subjected to a higher cracking temperature.

A portion of the re-run gas oil cut is recirculated through the fractionating tower by means of pump 23 taking suction through pipes 20, 24 and valve 24 and discharging through pipe 25 to the spray connection 26 in the fractionating tower 17. There is also a vapor cut taken from the tower 17 which is conducted by pipe 35 to the condenser 36 where the vapor is condensed, the condensate being conducted to the light oil tank through pipe 37 and look box 38, any uncondensed gases passing out of the look box 38 through the pipe 39 to the gas header 40.

The above ldescription Will give a clear idea of the operation of the process wherein a heavy oil and a gas oil are processed. The operation when gas oil alone is used is very similar to the above operation as for instance,

the re-run gas oil tank and from the gas` pipe 20 and 22 oil supply tank, while pump 304 is handling. oil from the heavy oil tank. It will also be observed that pump 21 can handle re-run gas oil, taking the make-up oil from lthe gas oil supply tank'to keep the system fully charged without the assistance of pump 30'. In this method of operation pump 21 only is used as a charging pump, taking its make-up oil from the gas oil supply tank through pipe 4l and connection 27 and valve 27', and at the same time takes suction from the re-run gas oil tank through and valve 22 and discharges it through pipe 28 and exchanger 15 and (or) by-pass 29 thence to the economizer coil 6 through valve 11 with valve 11 closed and discharges it through the valved connection 55 into coil 2, thence through crossover connection 2 into coil 4 and to the final passes 5 ofcoil 4. As the oil enters the final passes 5 the oil meets an advancing stream of oil which has been lay-passed from the original stream of oil entering the apparatus and, may be ley-passed through any of thel valves 54', 8', 9, 56 into the header 7 and through valve 10 and connection 10 into the final passes 5 of coil 4 where it meets the stream advancing` through coil 4. The admixed streams now pass through the final passes 5 of'coil 4 and discharge through pipe 12 to' the reaction chamber and heat exchanger 15 or direct to the heat exchanger, as previously described, thence to the pressure reducingand discharge valve 16 in pipe 16 and discharge( into the fractionating tower' where the oil is fractionated as previously described.

' If .I wish to inject relatively cold oil into thel openvalve 56 connecting the inlet pipe of the heater -to header 7 and have the valves 54', 8', 9 closed. From header 7 the oil may be discharged through valve 10- and connection 10 into the nal passes 5 as previously described. y If\I wish to by-pass heated oil to the final passes 5, Ican introduce oil heated in a graduated degree by having valve 56 closed and opening valve 54 whereby the temperature of the oil lay-passed would have the temperature attained in the economizer coil 6, or if a higher temperature were desired, I would openvalve 8 which is further advanced in the series of coils and obtain a by-passed portion of oil at a higher temperature than that `obtained through valve 54. Also in like manner I could obtain a still higher temperature in the by-passed portion of oil by tapping the` coil at any point desired as the oil progressed through the heating Coil.v Such a connection is shown at 9 and valve 9 and is shown as a single connection but is indicative of any number of by-pass connections and to show them would be a useless repetition. In this manner I am enabled to obtain a wide range of temperatures in ltheby- 4, there meeting the main stream of crac oil emerging from coil 4, it willbe increased 12,5

passed oil entering the'final passes 5 to perform the. functions described in the foregoing specication.

If heavy oil or re-run gas oil or fresh gas 0 oil is circulated through the economizer coil 6, and the main stream passes directly to coil 2 andy thence to coil 4, While part of the oil from coil 6 is `mixed with the oil advancing throughrthe final passes of coil 4 thereof, the following will actually Itake place.

rIhe oil passing through the economizer coil is heated to a relatively lower temperature than the main stream and on mixing of y the two oils the temperatureof the oil heated in the economizer coil is raised to a crack- 30 ing temperature and cools the advancing stream from coil 4. As described previously this permits of an advantageous transfer of heat through the walls of the tubesin the final passes 5 preventing the deposition of 85 carbon, and yet permitting a sufiicient heating of the mixed oils to crack the uncracked oil and regulate the temperature of therexiting stream from the final-passes.

Other combinations of the charging yoil 9 may be made other than those above enumerated, as for instance, pump 30 could intro- X duce fresh gas oil into the system through the economizer coil, thence through header 7 and )connection 10 into the final passes 5, 95

while'pump 21 was handling re-run gas oil through the main heating and cracking system or pump 30^could introduce cold fresh gas oil direct into the final passes 5 through pipe 53 and valve 53 with valve 33 the economizer coil 6 in series with coils 2 and 4, or pump 30 could handle re-run gas oil direct to the finalpasses 5 through con- 1y to the final passes of coilf5. Pump 21 can 110 handle re-run gas oil or fresh gas oil or mixtures thereof, for introduction via heat exchanger 15 directly to. coil 2. The point of introduction of the oil into the nal passes will depend upon the character of the oil employed in order to allow the oil to receive sufficient heating for a sufficient length of time and also to allow the mixed oils to be heated up to their required temperature.

If I linject heavy oil into the means of pump 30 and discharge it through coil 6 and by-pass header 7, valve 10 and connection 10 into the final passes 5' of coil ked in temperature to a -cracking degree, the temperature of the heavy oil streambeing so regulated that its temperature will be below that of the main stream, andas the mixed closed, 10 and pump 21 handling re-run gas oil through nection"53, and pump 21 could handle fresh 105 system by stream heated to a cracking temperature of 130 the heavy oil passes through the final passes 5 it will be subjected to an increasing cracking temperature and also to a prolonged reaction time and will be able to vabsorb heat 5 of .reaction and the quantity of oil passing through the coil is so regulated that its final temperature emerging from the final passes 5 will not be substantially above the operating temperature of the -main stream of oil 0 entering the final passes 5. In this manner 5 products not in the original oil such as gasoline and an increased yield of intermediates, such as gas oil or recycle stock.

ln a similar manner the injection of rerun gas oil or fresh gas oil through coil 6 into the final passes 5 will bring about the same results, or if these oils are by-passed from coil 2 through header 7 and injected into the `final passes 5, the same result may be obtained as recited above. understood that combinationsof heavy oil, re-run gas oil and fresh gas oil can be made by the proper operation of the apparatus to make variations of the mixture of stocks vto yield the desired final products.

It can be seen that a very large number of combinations may be made with the two pumps and the two grades of gas oil and the heavy oil, all of which may be advantageous at times depending upon the stock used 5 and the Imethod of introducing the various oils to the heating and cracking system. It will be noted that water may be introduced into the coils for purging them of carbonaceous material by pump 2l taking suction on the water tank through pipe connection 57 and valve 57 with valve 22 closed. The water and steam and carbonaceous material, after passing through the coils is blown out to waste through the blow-off valve 48 and 5 or valve 47 It is to be understood, however,

that an auxiliary pump may be used for handling the water for the reason that pump 2l may be used for charging several units that would not require purging at the sa-me time, and a bad operative condition would be created if the same pump had to function as an oil charging pump and as a water purging pump at the same time. If an auxiliary water pump is used the water should preferably be introduced at a point beyond valves 28 and 29 into pipe 28 or beyond valve 33 in pipe 33 or beyond valve 53 in pipe 53.

While I have explained my invention in connection with its application to the high pressure system disclosed in my Patent 1,- 456,419, I do not limit myself to this system or to pressures stated therein. This invention is applicable to any system where oil passes through coils and is there heated to a It can be readily cracking temperature whether or not the cracking reaction is completed in the oils. It is applicable to any cracking system wherein a tendency towards deposition of carbon or the formation of carbonaceous materials occurs in the tubes. Its application to other systems, it is believed, will be obvious to those skilled in the art from the above disclosure.

I claim:

1. A process for cracking oil which comprises continuously flowing a-stream of oil through an elongated continuously heated passageway and heating the oil to a cracking temperature during its l:fiow therethrough, withdrawing from an intermediate point of said passageway a portion of the said stream of oil, and introducing the said withdrawn oil into said passageway at a point intermediate the said point of withdrawal and the outlet of said passageway.

2. A process for cracking oil which comprises continuously iowing a stream of oil through an elongated continuously heated passageway and heating the oil to a cracking temperature during its flow therethrough,

said passageway a portion of the said stream of oil, regulatingthe temperature of said withdrawn portion of oil, and' introducing the said withdrawn oil into said passageway at a point intermediate the said point of withdrawal and the outlet of said passageway. i

A process for cracking oil which comprises continuously flowing a stream of oil through an elongated continuously heatedV passageway and heating the oil to a cracking temperature during its iow therethrough, withdrawing from an intermediate point of said passageway a portion ofthe said stream of oil, introducing the said' withdrawn oil into said passageway at a point intermediate the said point of withdrawal a'nd the outlet of said passageway, and continuing the heating of the blended stream of oil during its furthenflow'through said passageway. 4

4. A process for cracking oil which comprises continuously iiowing a, stream of oil through an elongated passageway heated throughout its length and' heating the oil to the desired cracking temperature during its flow therethrough, withdrawing from an intermediate point of said passageway a port'on of the said stream of oil, continuing t e heating of the remaining stream to supply the endothermic heat ofthe cracking reaction and to obtain the desired cracking thereof, introducing the said withdrawn oil into the passageway at a point where the desired cracking of the said oil stream is substantially completed, and continuing the flow through said passageway of the blended stream of oil while continuing the heating to effect further cracking thereof.

"withdrawing from an intermediatey point of sageway at a point where the desired cracking of the said oil stream is substantially completed, regulating the temperature and volume of the withdrawn oil to obtain a temperature of the admiXed oil-formed on the introduction of the said withdrawn oil into the said passageway sufficient to crack the uncracked oil in the admixture, and continuing the fiowthrough said passageway of the blended stream of oil while continuing the heating. to effect further cracking thereof;

6. A process for cracking oil which comprises continuously flowing a stream of oil through an elongated' continuously heated passageway and heating the oil to a cracking ff vtemperature during its flow therethrough,

withdrawing from anL intermediate point of said passageway a portionof the said stream of oil, introducing the said withdrawn oil into said passageway at a point intermediate the said point -of withdrawalr and the outlet of said passageway, and maintaining the oil during its flow through said passageway under pressure sufficient to prevent substantial va orization thereof.

A process for cracking oil which comprises continuously flowing a stream of oil through an elongated continuously heated passageway and heating the oil to a cracking temperature duringits flow therethrough, withdrawing from an intermediate point o-f said passageway a portion of the said stream of oil, regulating the temperature of said withdrawn portion of oil, introducing the said. withdrawn oil into said passageway at a point intermediate the said point of withdrawal and the outlet of said passageway,

and maintaining the oil during its flow through saidpassageway under pressure sufcient to prevent substantial vaporization thereof. 8. A process for cracking oil which comprises continuously flowing a stream of oil through a coil mounted in a furnace, heating the oil during flow therethrough to a substantial cracking temperature, withdrawing a portion of the oil from said stream at an intermediate point of said coil, by-passing the withdrawn oil and introducing it into the' stream of heated oil at a point intermediate the said point-of withdrawal andthe outlet of said coil and atea point where the sald stream has attained a `substantial cracking temperature, and supplying additionalv heat to'ihe oil during its further flow through said co1 9. A process for cracking oil which comprises continuously flowing a stream of oil through a coil mounted in a furnace, heating the oil during flow therethrough to a sub- ,a

stantial cracking temperature, withdrawing a portion of the oil from said stream Lat an intermediate point of said coil before said vstream of oil has attained a cracking temperature, by-passing the withdrawn oil and introducing it into the stream of heated oil at a point intermediate the said point of withdrawal and the outlet of said coil, and at a point where the said stream has attained a substantial cracking temperature, and supplying additional heat to the oil during its further flow Ithrough said coil.

10. A process for cracking oil which comprises continuously flowing a stream of oil through a coil mounted in a furnace, heating the oil during flow therethrough to a substantial cracking temperature, withdrawing termediate point of said coil, by-passing the withdrawn oil and introducing itinto the stream of heated oil at a point intermediate the said pointof withdrawal and the outlet of said coil and at a point where the said stream has attained a substantial cracking temperature, regulating the temperature of said Icy-passed portion of oil to modify the tgmperature of the oil in the zone of introduction, and supplying additional heat to the1 oil during its further flow through said co1 11. A process for cracking oil which comprises continuously flowing a stream of oil through a coil mounted in a furnace, heating the oil during flow therethrough to a substantial cracking temperature, withdrawing a portion of the oil from said stream at anintermediate point of said coil, by-passing the withdrawn oil and introducing it into the stream of heated oil at a point intermediate the said point of withdrawal and the outlet'of said coil and at a point where the-saidzstream has attained asubstantial cracking temperature, regulating the temperature and volume of said by-passed portion of oil to modify the temperaturelof the oil 1n the zone of introductiom'and supplying additional heat to thev oil during its further flow through said coil. v 5

12. A process for cracking oil which comprises continuouslylflowing a stream of oil through a coil mounted in a furnace, heating the oil during lflow therethrough to a substantial cracking temperature, withdrawing a portion of the oil from said stream at an intermediate point of said coil, by-passing the withdrawn oil .and introducing it into the stream of heated oil at a point' intermediate the said point of withdrawal and the out-I a portion of the oil from said stream at an inv90 let of said coil and at a point where the saidk stream has atta-ined a substantial cracking temperature, regulating the temperature and volume of said by-passed portion of oil to modify the temperature of the oil in the zone of introduction, supplying additional heat to the oil during its further flow through said coil, and maintaining a pressure on the oil during` its iow through said coil sufficient to prevent substantial vaporization of said oil.

13. A process for cracking oil which comprises heating a stream of oil flowing through a coil mounted in a furnace to a temperature suliicient to crack it and under pressure suflicient to prevent material vaporization, Withdrawing a portion o'f the oil from an intermediate'point of the coil before reaching its cracking temperature, by-passing the withdrawn oil and reintroducing it into the heated stream of oil passing through the coil at a point subsequent to the point of withdrawal,

, continuing the flow of the stream through stream of oil passing through the coil at a point subsequent to the point of withdrawal and after the heated stream of oil has attained Aa cracking temperature, continuing the flow of the stream through said coil and supplying additional heat theretolwhile maintaining the said stream under said pressure.

.15. Aprocess for cracking oil which corni prises heating a stream of oil flowing through a coil mounted in a furnace to a temperature sufficient to crack it and under pressure suiicient to prevent material vaporization, withdrawing a'portion of the oil from an intermediate point of the coil before reaching its cracking temperature, by-passing the withdrawn oil and reintroducing it into the heated stream of oil passing through the coil at a point subsequent to the point of withdrawal, continuing the How of the stream through said coil, supplying additional heat thereto while maintaining the said stream under said pressure, and conducting the stream of oil to a fractionating device and fractionating the oil.

164 A process of cracking hydrocarbon oils l comprising, heating oil under superatmospheric pressure while passing once through a continuous heating coil mounted in a furnace, continuing the supply of heat to the oil passing through the coil for a prolongedv period of time to maintain it at a substantially' constant cracking temperature, withstream to` check the cracking reaction of the heated portion of the main stream of oil, and continuing the flow of the blended oil stream through said coil while supplying additionall heat thereto to effect further cracking thereof.

17. A process of treating oil comprising passing the oil through a coil mounted in a furnace and simultaneously heating the same to a temperature suiiciently high to crack the oil and under pressure suiciently high to prevent material vaporizationof the oil, withdrawing a portion of the oil from an intermediate point of the coil before it has been cracked, then introducing the cooler, withdrawn, uncracked oil at a point in the path of flow of the oil through the coil subsequent to the said point of withdrawal in quantities suflicient to check the cracking of the main stream of oil by reducing the temperature thereof, continuing the flow of the s, blended stream through said coil while supplying additional heat thereto to elfect further cracking thereof while maintaining said pressure on the blended stream, releasing the pressure on said stream of oil and discharging it into a fractionating apparatus to fractionate the same.

In testimony whereof I afliX my signature.

JHN C. BLACK.

lll() 

